Hitherto, a worked beryllium-copper alloy prepared by adding beryllium to copper has exclusively been used for wire products required to have high strength and high conductivity. On the other hand, precipitation type alloys have been seldom used in the field of wires.
However, the conventional wires, represented by wires using beryllium copper alloy, have involved the following problems:
(1) Beryllium copper alloy is more expensive than alloys such as phosphor bronze;
(2) Hygiene and safety problems for the workers may arise with use of beryllium, a harmful substance;
(3) While phosphor bronze is used as a substitute for beryllium copper alloy, both the conductivity and strength of the former are low;
(4) The strength of a low-beryllium copper alloy (a beryllium content of 1.0% by mass or less) is low; and
(5) While high-beryllium copper alloy (a beryllium content of 1.5% by mass or more) has low conductivity and high strength, the quality is too good for the recent service life of the product.